Method for cutting up plastic and semi-plastic masses



April 14, 1959 c. o. JO NSON 1,5

mamou FOR-CUTTING UP PLASTIC AND SEMI-PLASTIC MASSES Filed uarch'ls,i956 United States Patent METHOD FOR CUTTING UP PLASTIC AND SEMI-PLASTICMASSES Carl Olof Johnson, Skovde, Sweden, assiguor to DuroxInternational S.A., Luxembourg, Luxembourg, a company of SwedenApplication March 13, 1956, Serial No. 571,276 Claims priority,application Sweden March 16, 1955 4 Claims. (Cl. 25-155) The presentinvention refers to cutting up plastic or semi-plastic masses,particularly in connection with the manufacture of light weightconcrete.

In the manufacture of light weight concrete, the material to be used,admixed with comparatively large amounts of water, is poured into molds,the size of which is usually considerably bigger than thesize of thebuilding blocks to be manufactured; The mass is expanded e.g. by meansof aluminum powder and when it has become so hard that it issemi-plastic and unyielding, it can be cut up into smaller units.

The cutting up can be made in different Ways. Originally it was effectedby pressing down some kind of cutting device, e.g. thin plates into thelight weight concrete mass. The blocks manufactured in this manner,however, did not have sufliciently exact dimensions, and the surface ascut up was so smooth that it did not offer a satisfactory base for beingplastered. When manufacturing blocks in comparatively deep molds, thismethod was found to be quite unsatisfactory, and therefore it was triedto solve the cutting up problem in other ways.

The cutting up method which is at present most frequently used iseffected by letting down the mold walls and sawing the light weightconcrete mass by means of wires provided with projections, e.g. balls.This method has considerable advantages over the cutting up 'method bymeans of thin plates, but involves several inconveniences. Thus, theletting up and down of the mold walls requires comparatively much workand time. The material which loosens at the sawing sticks fast to thesawing device and necessitates frequent cleaning. When using big moldsit has been found that the precision of the dimensions of themanufactured blocks is not satisafctory.

According to the present invention all said drawbacks can be avoided,and simultaneously the cutting up device is simpler and independent ofthe construction and size of the molds. This is according to theinvention obtained by cutting by means of a thin jet of a fluid, aliquid or a gas, having a high speed, which is directed towards the massto be cut up and is moved along the line where the cutting is to beeffected. Owing to the moving force of the liquid or gas the jet willmake a channel in the porous light weight concrete mass, and as thefluid nozzle and the light weight concrete mass move mutually, therewill be formed a slit in the mass. By increasing or decreasingrespectively, the velocity of the fluid, its depth of penetration may bevaried, or the cutting velocity may be increased or decreased,respectively. The same effect may be obtained by keeping the speed offlow constant while varying the specific gravity of the fluid. -In casethe fluid consists of a gas the specific gravity may be increased byusing a gas having a higher specific gravity or by dispersing liquid orsolid particles in the gas. In case of a liquid a higher specificgravity can be obtained by using a different liquid or by dissolvingsalts in the liquid, or by dispersing a solid substance in the liquid.Water has been found to be the most suitable medium for cuttingaccording to the present method. It has been found that also be flat,being then suitably extended the water used for cutting is totallyabsorbed by the porous light weight concrete. The water thus absorbedinvolves an advantage, since it reduces the deficiency of water whichwill easily arise when the light weight concrete mass is setting. It isof course also possible to influence the cutting velocity by arrangingseveral consecutive nozzles so that they work in the same cut, or byshaping the orifices of the nozzles as slits.

When cutting very deep cuts it is also possible, besides the abovemethod using a plurality of nozzles working in the same cut, to make thenozzle pass the same cut several times.

When coordinating a plurality of nozzles for making one cut the firstnozzle should preferably be arranged adjacent to the body to be cut up,whereas the following nozzles are inserted into the cut produced by thefirst nozzle.

The nozzzles may be arranged in any position relative to the body to becut, above, below or beside it. When using the type of molds which istraditionally used for the light weight concrete manufacture it isconvenient to have the nozzles situated above the light weight concreteblock to be cut up. The nozzles may also be made movable so that thedirection of the jet may be altered. This makes it possible tomanufacture blocks having extremely varying shapes, using one cuttingdevice, which was earlier impossible.

The jet of fluid is preferably circular, but may of course in thecutting direction, at least if the width is essential. As a principle,the thickness of the jet should be as small as possible, but the smallerthe thickness, the higher the demands for a high pressure, determiningof course a lower thickness limit. A jet thickness above 5 millimetersis probably out of question. In case water is used for the jet, saidwater will be absorbed by the concrete mass, up to a certain extent,depending on the dryness of the mass. If the jet thickness exceeds acertain value, some water will flow away. If a considerable amount ofwater flows away, difficulties may arise, determining an upper limit forthe jet thickness. Practically, a jet thickness of 0.52 millimeters hasbeen found to be suitable when using a water jet.

The invention will be hereinafter described more in detail withreference to the drawing which shows an elevation of an apparatus forcarrying out the method according to the invention.

In the drawing 1 designates the bottom portion of a mold, the walls ofwhich have been removed. The bottom 1 carries a light weight concretebody 2, and is supported by supporting members 3, secured to a wheeledframe or carriage 4.

Water tubes 5 and 7 respectively, are provided above and below theconcrete body 2, respectively, each tube having eight nozzles 6 and 8,respectively. The tubes are guided in brackets 9 and 10, respectively soto be movable longitudinally. Said longitudinal movement is effected bymeans of a guide member 11, engaging with arms 12 and 13 secured to thetubes 5 and 7, respectively. The guide member 11 extends longitudinallyalong the whole length of the block 2, and is secured to the supportingmember 3. Consequently, the guide member 11 accompanies the body 2 inits movement during cutting. It will easily be understood that the shapeof the longitudinal cuts in the body 2 will depend on the shape of theguide member 11. By suitably shaping the guide member longitudinal cutsof any desired shape may be performed. In the illustrated embodiment,the central portion of the guide member has a bent portion 24.Accordingly, the longitudinal cut will obtain a portion which iscorrespondingly bent.

When operating the illustrated apparatus high pressure water is sprayedthrough the nozzles 6, 8, and the block is propelled'longitudinally bymeans of the wheeled frame 4. The jets from the nozzles 8 penetrate intothe light weight concrete through longitudinal openings 14 in the bottomportion 1. 'In case a bottom portion is used having no such openings thenozzzles 8 are shut off, and the cutting up is effected by means of thejets from the nozzles6.

If desiretL the nozz'les 6, 8 may be arranged so as to be turnable inthe transverse direction. By this,'the apparatus may easily be alteredso as to manufacture smaller light weight concrete pieces of a difierentshape.

'The high pressure water is generated by a pump 16, driven by a motor15. The water flows through a water pressure chamber 17, provided with apressure indicator 22 and a levellindicator 23, and if desired with apressure regulator, and through a pipe 19, provided with a valve 18, andthrough flexible tubes 20, 21'into the tubes and .7, respectively.

What is claimed is:

l. A method of cutting a mass of light weight concrete in its set butunhardened state comprising the step of directing a jet of a fluidsubstantially consisting of an aqueousliqui'd into the concrete mass,the amount of said liquid being so limited that the liquid will besubstantially completely absorbed by the walls of the cut surfaces ofsaid mass.

2. The method of cutting a mass of light weight concrete in its set butunhardened state comprising the step of directing into the concrete massa jet of approximately 2 .millimeter thickness substantially consistingof an aqueous'liq11id,the amount of said liquid being so limited thatthe liquid will be substantially completely absorbed by the walls 'of'the cut surfaces of said mass.

3. The method of cutting a mass of light weight concrete in its set but'unhardened state comprising the step of directing a jet of afluidisubstantially consisting of an aqueous liquid into the concretemass, the amount of said liquid being so limited that the liquid will besubstantially completely absorbed by 'the'wall's of the cut surfaces ofthe mass, moving said concrete mass relative to said liquid jet, andvarying the cutting force -of said fluid jet by varying the specificgravity of the fluid.

4. 'The method of cuttinga'mass of light Weight'concrete in its set butunhar'dened state comprising the step of directing into the concretemass a jet of approximately 2 millimeter thickness of a fluidsubstantially consisting of an .aqueous liquid, the amount of saidliquid being so limited that the liquid will 'be substantiallycompletely absorbed by the :Walls of the cut surfaces of said mass,moving said concrete mass relative to said liquid jet, and

dissolving salts in said liquid to vary the cutting force of said fluidjet by variation of the fluid gravity of theliquid thereof.

References Cited in the file of this patent UNITED STATES PATENTS"1,'504;645 Rice Aug. 12, '1924 092,083 Ogle-et a1. 'Sept. 7, 19372,489,784 Kerr Nov. '29, 1949 2,694,846 -Olssonet al. 'Nov. '23, 19542,696,049 Black Dec. '7, 1954 FOREIGN PATENTS 843,130 France Mar. 20,1939

